How to Use Old .NetMap Workbooks With the Latest .NetMap Version

If you're using .NetMap version 1.0.1.57 or later and you try to open a .NetMap workbook that was created with version 1.0.1.56 or earlier, you'll get a couple of baffling error messages from Excel:

"There was an error during installation."

followed by

"The customization assembly could not be could not be found or could not be loaded."

The problem occurs because I changed the way the .NetMap setup program works in version 1.0.1.57. The new setup is a big improvement over the old one, but as a side-effect it changed a custom property hidden in each workbook that tells Excel where to
find the .NetMap program. When Excel goes looking for .NetMap in the old location and fails to find it, it complains with the messages shown above.

The good news is that this won't occur going forward. Workbooks created with version 1.0.1.57 or later should be forward-compatible with future versions. The bad news is that to use an old workbook, you have to either copy-and-paste its data to
a new workbook, or manually change the custom property in the old workbook. Here is the procedure required to change the custom property. It looks complicated, but that's only because custom properties are buried in Excel and it takes several clicks
to find them.

If there is enough demand for it, I can write a small program that runs this procedure automatically.

-- Tony

Procedure to Fix the Problem

In Excel, open the old workbook. When you get the "There was an error during installing" message, click Close. When you get the "The customization assembly could not be could not be found or could not be loaded" message,
click OK.